The present invention relates to a device for connecting two rotary parts so that one of such parts can transmit torque to the other part. More particularly, the invention relates to improvements in connections between drive shafts and mandrels or like rotary components which can be used as a means for collecting or paying out flexible webs consisting of paper, textile, material metallic or plastic foil or the like. Still more particularly, the invention relates to improvements in connections or coupling of the type wherein at least one end portion of the driven component has a polygonal outline and fits into the complementary cavity of a socket which forms part of or rotates with the driving component.
Couplings of the above-outlined character are used in many industries, e.g., in the paper processing industry, to enable a mandrel, core, spindle or an analogous rotary part (hereinafter called mandrel) to gather or dispense a flexible web. The same holds true for the manipulation of convoluted webs of textile material. A connection of conventional design is described, for example, in German Pat. No. 917,592. This publication discloses a so-called foldable bearing which includes a socket serving to receive, with substantial tolerance, the polygonal end portion of a mandrel. Pronounced tolerance is desirable and necessary because one and the same bearing is used to accept and to transmit torque to a substantial number of different mandrels. Thus, were the tolerances negligible or non-existent, it would be highly unlikely that one and the same socket could receive the polygonal end portions of two, three or a much larger number of different mandrels. On the other hand, pronounced tolerances exhibit a number of serious drawbacks. Thus, the mandrels are likely to wobble or perform other undesirable stray movements which promote wear and cause readily detectable noise. The mandrels run out of true (i.e., their axes do not coincide with the axes of the driving shafts), and this can affect the quality of the winding or unwinding operation. The noise which develops as a result of wobbling of a mandrel with respect to the socket or sockets for its polygonal end portion or portions is especially undesirable and highly pronounced when the mandrel is long and bulky, i.e., when the weight of the mandrel is substantial and such mandrel must be driven at a high speed. Additional causes of noise are the tension to which a web of convoluted material must be subjected, either during winding onto the mandrel or while the mandrel is rotated in a direction to pay out the convoluted material.